JP6840315B2 - Sheet-shaped air electrode manufacturing method, acid battery and power generation system - Google Patents

Description

The present invention relates to a sheet-shaped air electrode used for a positive electrode of a battery (acid battery) using an acidic electrolyte, an acid battery, and a power generation system for realizing the same on a relatively large scale.
In particular, the present invention relates to a sheet-shaped air electrode composed of a carbon fiber sheet having a film-like material containing carbon nanotubes on its surface, an acid battery, and a power generation system.

Batteries include physical batteries (optical batteries, solar cells) and chemical batteries. Chemical batteries include primary batteries that generate electricity and discharge by themselves, secondary batteries that store and discharge electric power given from the outside, and fuel cells.
Since the secondary battery can be repeatedly charged and discharged, it can be used repeatedly. On the other hand, primary batteries are often said to be unchargeable, but can be used repeatedly by mechanically replacing substances that have been reduced by use (mechanical culture).

As an example of a primary battery that can be used repeatedly, one using magnesium or aluminum as a negative electrode and an acidic electrolyte has been proposed (Patent Document 1).
In Patent Document 1, magnesium or aluminum is used as a negative electrode, a conductive member (carbon sheet) is used as a positive electrode, air is supplied to the positive electrode, and an acidic electrolyte composed of perchloric acid is disposed between the negative electrode and the positive electrode. , An acid battery that can be continuously used by simply replacing the metal of the negative electrode with a new metal is disclosed.
Further, in this acid battery, the chemical reaction can be completely stopped by breaking the contact between the negative electrode and the electrolyte.
The positive electrode in Patent Document 1 is described as a carbon-based conductive member such as carbon.

On the other hand, carbon has a plurality of allotropes having significantly different properties such as graphite, diamond, and amorphous carbon. It has been confirmed that nanometer-sized carbon allotropes, which have been newly discovered since the 1980s, have completely different atomic structures and physical properties from the conventionally known carbon allotropes, and their high industrial utility value is noteworthy. Has been done. In the present specification, they are referred to as "nanocarbon materials", and are carbon nanotubes, carbon nanofibers, nanographenes, fullerene, carbon nanohorns, carbon microcoils, carbon black, diamond-like carbon, carbon nanocrystals, activated carbon, etc. It shall include those having a size of about nm to 10 μm.

Since the nanocarbon material is composed only of carbon, it is an extremely lightweight, high-strength, conductive polymer material. Its conductivity is superior to copper, its strength is superior to steel, it has high heat resistance, it does not react with many chemicals, and it is stable in the atmosphere.
Among nanocarbon materials, carbon nanotubes exhibit particularly excellent electrical properties, mechanical properties, thermal properties, etc., and are expected to be applied to various materials, and are widely researched and developed. For example, materials for various purposes can be obtained from a composite material in which carbon nanotubes and a resin are mixed, or a material in which a carbon nanotube dispersion liquid is mixed with a binder and dried.

Since carbon nanotubes have the property of aggregating due to van der Waals force and form a bundle structure in solution, it is not possible to produce a good carbon nanotube composite material as it is, and carbon nanotubes are dispersed in solution ( Alternatively, a step of solubilizing) is required. Since the use of a solution (dispersion solution) in which carbon nanotubes are well dispersed greatly contributes to the improvement of the characteristics of the carbon nanotube composite material, many proposals have been made regarding a technique for stably dispersing carbon nanotubes in the solution. ing.

As a method for dispersing carbon nanotubes in a solution, a method using an organic solvent (for example, N-methylpyrrolidone; NMP), a method for chemically modifying carbon nanotubes by acid treatment, a surfactant (for example, sodium dodecyl sulfate; SDS) There is a method of forming micelles, and in many cases, ultrasonic treatment and bead mill treatment are also used in combination.

Patent Document 2 proposes a carbon nanotube dispersion liquid containing a surfactant having an alkyl ester group, a vinylidene group and an anionic group, carbon nanotubes, and an aqueous solvent (claim 1 and the like). In this dispersion technology, it is said that the carbon double bonds of the vinylidene group of the surfactant interact with the carbon nanotubes to promote the dispersion of the carbon nanotubes, such as conventional sodium dodecyl sulfate (SDS). A carbon nanotube dispersion liquid having a higher degree of dispersion ([0055] to [0062], etc.) and higher stability to pH changes ([0063] to [0069], etc.) than when a dispersant is used can be obtained. The result is reported.

Patent Document 3 proposes a composite material of carbon nanotubes and activated carbon.

Japanese Patent No. 5385569 Japanese Unexamined Patent Publication No. 2010-13312 Japanese Unexamined Patent Publication No. 2006-45034

The carbon nanotube dispersion liquid using an organic solvent such as NMP or a surfactant such as SDS has a problem that the carbon nanotubes agglomerate again with the passage of time, and the organic solvent and the surfactant are impurities in the produced nanocarbon material. The problem of remaining as is not solved.
The method of chemically modifying carbon nanotubes by acid treatment is to introduce a functional group having an affinity for a solvent into the surface of the carbon nanotubes in a covalent bond, but this causes the carbon nanotubes to lose their original properties or to be cleaved. The problem that it has been done has not been solved.

The present invention has been made in view of the fact that there is a problem of dispersion in utilizing the excellent characteristics of carbon nanotubes, and if the problem can be overcome, it is considered to be effective for a carbon sheet as a positive electrode of an acid battery. A method for dispersing nanocarbon materials and a dispersion liquid for nanocarbon materials, which can maintain a good dispersed state over time without impairing the original properties of carbon nanotubes, and obtained by them. We propose a nano-carbon material composite that can be used as a positive electrode for an acid battery by forming the carbon material composite into a film and covering the surface of the carbon fiber sheet.
Furthermore, we propose a power generation system that can realize planned power generation that generates the required amount of power according to the demand for power.

As a result of diligent research in view of the above-mentioned problems, the present inventor
(1) Carbon nanotubes and carbon nanotubes in a solvent in which 0.01 to 10% of anionic surfactant or nonionic surfactant is added to an aqueous solution containing 10% by weight or more of lower alcohol. On the other hand, 1 to 30% by weight of other types of nanocarbon materials such as graphene, carbon black, and activated carbon containing one or more of them are added as an anti-aggregation agent, and ultrasonic waves are added to the obtained solution (slurry). Dispersion processing is performed by irradiating.
(2) The slurry of the above (1) is added to an aqueous solution containing a suitable surfactant, and the raw material aqueous solution (1 to 5 parts by weight of carboxymethyl cellulose ammonium and 1 to 5 parts by weight of ammonium hydrogen carbonate with respect to 1 part by weight of carbon nanotubes). , A polyol (including a polyol), and it was found that a dispersion liquid of a nanocarbon material having extremely excellent dispersibility can be obtained by performing ultrasonic treatment.
Further, he came up with the idea that a film-like material containing the carbon nanotubes was provided on the surface of the carbon fiber sheet to form a fiber-bonded 3D mesh to serve as a positive electrode of an acid battery, and the present invention was achieved.

The sheet-shaped air electrode according to the present invention is made of a carbon fiber sheet having a film-like substance containing carbon nanotubes on its surface.
This makes it possible to construct an air electrode that takes advantage of the characteristics of carbon nanotubes such as ion permeability, conductivity, and oxygen permeability.

Further, the area, size, shape, and three-dimensional deformation processing of the carbon fiber sheet can be changed according to the spatial shape of the place where the carbon fiber sheet is arranged. This makes it possible to customize the shape of the battery, and the size, shape, etc. can be freely selected.

In particular, it is used as a positive electrode for acid batteries. This makes it possible to construct an acid battery which is advantageous in terms of current density and the like.

Further, the negative electrode of the acid battery is made of a metal containing one or more of magnesium, aluminum, zinc, iron or copper, and an acidic electrolyte is arranged in a space where the positive electrode and the negative electrode are close to each other. As a result, the metal of the negative electrode is melted (corroded) by the acid to form a battery.

The acidic electrolyte is a solution, and the electrolyte of the solution can permeate the carbon fiber sheet into contact with the negative electrode. This allows the electrolyte and dissolved oxygen in the solution to move and function in the solution.

The circulation device for circulating the solution allows the electrolyte and the dissolved oxygen in the solution to permeate and circulate through the carbon fiber sheet. This makes it possible to eliminate products from chemical reactions and to carry the required electrolytes and dissolved oxygen where they are needed.

Circulation by the circulation device can be controlled, thereby stopping the electrolyte from circulating through the carbon sheet or reducing the supply of dissolved oxygen in the solution. This makes it possible to stop or slow down the chemical reaction.

The acidic electrolyte is a gel and can be provided as a gel sheet impregnated in the sheet. This prevents dripping and allows the product to be used without worrying about the orientation of the liquid.

The gel comes into contact with the negative electrode via a blocking sheet that does not allow electrolytes to permeate and can be inserted and removed, generates electricity with the blocking sheet removed, and can stop power generation with the blocking sheet inserted. This makes it possible to avoid unnecessary discharge when not in use.

The gel sheet can be inserted and removed, and by removing the gel sheet, the contact between the acidic electrolyte and the negative electrode is cut off, and by inserting the gel sheet, the contact between the electrolyte and the negative electrode is realized. As a result, the discharge of the battery can be stopped or slowed down, and the battery can be used again when necessary.

The negative electrode is replaceable, and when it is dissolved, it can be replaced with a new negative electrode. This makes it possible to realize a primary battery that can be used repeatedly.

The acid battery according to the present invention has a sheet-like air electrode made of a carbon fiber sheet having a film-like material containing carbon nanotubes on its surface as a positive electrode, and a metal containing magnesium, aluminum, zinc, iron or copper as a negative electrode. An acidic electrolyte is arranged between the positive electrode and the negative electrode. This makes it possible to construct an acid battery that takes advantage of the characteristics of carbon nanotubes.

The area, size, and shape of the carbon fiber sheet can be changed according to the spatial shape of the place where the carbon fiber sheet constituting the positive electrode is arranged, and the negative electrode can be changed according to the change in the area, size, and shape of the positive electrode. Transforms. This makes it possible to provide an acid battery that can be installed even in a narrow place or a curved place.

The acidic electrolyte can be a solution. This makes it possible to construct a battery that is advantageous in removing the product after the reaction and moving the electrolyte and the dissolved oxygen in the solution to the required place.

A circulation device for circulating the solution can be further provided so that the electrolyte and the dissolved oxygen in the solution can be circulated. This makes it possible to provide a battery capable of efficiently performing a chemical reaction.

The circulation by the circulation device can be controlled, the circulation of the electrolyte can be stopped, or the supply of dissolved oxygen in the solution can be reduced. This makes it possible to stop or slow down the chemical reaction.

The acidic electrolyte is in the form of a gel and can be provided as a gel sheet impregnated in the sheet. This makes it possible to prevent dripping. Moreover, the direction in which the battery is placed is not limited.

The gel sheet comes into contact with the negative electrode via a blocking sheet that does not allow electrolytes to permeate and can be inserted and removed, generates electricity with the blocking sheet removed, and can stop power generation with the blocking sheet inserted. As a result, wasteful discharge when not in use can be avoided.

The gel sheet can be inserted and removed, and by removing the gel sheet, the contact between the electrolyte and the negative electrode is cut off, and by inserting the gel sheet, the contact between the electrolyte and the negative electrode is realized. This makes it possible to prevent unnecessary discharge when the battery is not used.

The negative electrode is replaceable, and when it is dissolved, it is replaced with a new negative electrode. This makes it possible to provide an acid battery that can be used repeatedly.

The power generation system according to the present invention has a sheet-like air electrode having a film-like material containing carbon nanotubes on its surface as a positive electrode, and a metal containing one or more of magnesium, aluminum, zinc, iron or copper. Is used as the negative electrode, and a plurality of acid batteries in which an acidic electrolyte is arranged between the positive electrode and the negative electrode are arranged in a laminated manner and electrically connected.

A carbon fiber sheet is used as the base material of the air electrode forming the positive electrode. As a result, the surface area can be increased, which is advantageous in promoting the reaction.

The area, size, and shape of the carbon fiber sheet constituting the positive electrode can be changed according to the spatial shape of the place where the positive electrode is arranged, and the negative electrode is deformed according to the change in the area, size, and shape of the positive electrode. .. This makes it possible to customize the shape of the acid battery.

The acidic electrolyte is a solution. This is advantageous for the removal of reactive organisms and the transfer of dissolved oxygen in the electrolyte and solution.

A circulation device for circulating the solution is further provided so that the electrolyte and the dissolved oxygen in the solution circulate. Thereby, the chemical reaction can be promoted.

The circulation by the circulation device can be controlled, the circulation of the electrolyte can be stopped, or the supply of dissolved oxygen in the solution can be reduced. This allows the chemical reaction to be stopped or slowed down.

The acidic electrolyte is in the form of a gel and is provided as a gel sheet impregnated in the sheet. This prevents dripping and removes restrictions on the orientation of the power generation system.

The gel sheet comes into contact with the negative electrode via a blocking sheet that does not allow electrolytes to permeate and can be inserted and removed, generates electricity with the blocking sheet removed, and stops power generation with the blocking sheet inserted. This avoids unnecessary discharge when not in use.

The gel sheet can be inserted and removed, and the contact between the electrolyte and the negative electrode is cut off by removing the gel sheet, and the contact between the electrolyte and the negative electrode is realized by inserting the gel sheet. This prevents unnecessary discharge when electricity is not used.

It has a reaction stop device that cuts off the contact between the negative electrode and the acidic electrolyte, or cuts off the contact between the positive electrode and oxygen. This prevents unnecessary discharge when electricity is not used and enables planned power generation.

The reaction stop device can release the reaction stop state and start power generation again. This makes it possible to freely control the use and non-use of electricity.

A sheet-like air electrode having a film-like material containing carbon nanotubes on its surface is used as the positive electrode, and a metal containing one or more of magnesium, aluminum, zinc, iron or copper is melted. It is provided interchangeably with a new one to serve as a negative electrode, and a separator having electrical insulating property and transmitting an electrolyte is provided between the positive electrode and the negative electrode, and the positive electrode, the separator, and the negative electrode are laminated and arranged. A power generation system may be provided with an acidic electrolyte supply device that drops or sprays an amount of acidic electrolyte necessary for power generation from the positive electrode side of the object to reach the negative electrode. This allows a lean acidic electrolyte supply to prepare the necessary and sufficient fire to burn the firewood.

It further has an acidic electrolyte supply control device that controls the supply amount of the acidic electrolyte by the acidic electrolyte supply device, and realizes planned power generation. This makes it possible to deal with power outages and power shortages in midsummer.

The method for producing a sheet-shaped air electrode made of a carbon fiber sheet having a film-like substance containing carbon nanotubes on its surface according to the present invention is to dissolve carbon nanotubes, carboxymethyl cellulose ammonium, ammonium hydrogen carbonate and glycerin in water. The raw material aqueous solution generation step of making the raw material aqueous solution, the ultrasonic irradiation step of irradiating the raw material aqueous solution with ultrasonic waves with an ultrasonic homogenizer to obtain a dispersed aqueous solution, and impregnating the carbon fiber sheet with the dispersed aqueous solution after the ultrasonic irradiation. It has an impregnation step for allowing the carbon fiber sheet to be impregnated and a drying step for drying the carbon fiber sheet after impregnation. This makes it possible to bring out the original properties of carbon nanotubes.

The impregnation step and the drying step are repeated (for example, 3 times). Thereby, the coating (film-like material) of carbon nanotubes can be effectively provided on the surface of the carbon fiber sheet.

As described above, according to the present invention, it is possible to configure an electrode, a battery, and a power generation system that make use of the inherent properties of carbon nanotubes.

It is a figure which shows the example of the carbon fiber sheet which becomes the base material of an air electrode. It is a figure which shows the state that the sheet-shaped air electrode (positive electrode) overlaps with the negative electrode through a separator sheet, and is laminated. It is a figure which shows the deformation processing at the time of forming an acid battery which is wound around a pipe and arranged. It is a figure which shows the system which circulates an electrolyte and controls the start, stop, and restart of power generation. It is a figure which shows that the start, stop, and restart of power generation are controlled by using a cutoff sheet when a gel sheet is used. It is a figure which shows that when the gel sheet is used, the start, stop, and resumption of power generation are controlled by inserting and removing the gel sheet itself. It is a figure which shows the structure in the case of dropping or spraying an acidic electrolyte from a positive electrode side.

Hereinafter, referring to the attached drawings, the best method for realizing the nanocarbon material dispersion method, the nanocarbon material dispersion liquid, and the nanocarbon material composite of the present invention, and realizing an air electrode, an acid battery, and a power generation system. The form will be described in detail.
The order of explanation is the table of contents, with the titles listed.
≪Manufacturing method of sheet-shaped air electrode by dispersion, coating, impregnation and drying of carbon nanotubes≫
≪Sheet-shaped air electrode and its deformation processing≫
≪Positive electrode and positive electrode active material of acid battery≫
≪Negative electrode and negative electrode active material of acid battery≫
≪Acid electrolyte≫
≪Circulate acidic electrolyte solution and control it≫
≪Gel-like electrolyte and power generation stop, power generation restart≫
≪Scalability by stacking≫
≪Planned power generation by dropping or spraying acidic electrolyte solution≫

≪Manufacturing method of sheet-shaped air electrode by dispersion, coating, impregnation and drying of carbon nanotubes≫
As an example of the nanocarbon material dispersion method, the nanocarbon material dispersion liquid and the nanocarbon material composite of the present invention, specific production methods of the nanocarbon material dispersion liquid and the nanocarbon material composite and the physical properties indicated by them. The test results will be described.

<Adjustment of dispersion liquid 1 and CNT-coated carbon fiber 1>
Preparation of Aqueous Solution of Raw Materials As carbon nanotubes, multi-walled carbon nanotubes (NC7000 (average diameter 9.5 nm, average length 1.5 μm, specific surface area 250 to 300 m ² / g, carbon purity 90%) manufactured by Nanocil) were used.
As the carboxymethyl cellulose ammonium, the product name "CMCA25" (25% hydrate of carboxymethyl cellulose ammonium) manufactured by Fine Clay Co., Ltd. was used.
As ammonium hydrogencarbonate, a product of Ube Industries, Ltd. (product code: IO-B14-0016), purity 95.0% or more) was used.
An aqueous solution of raw materials was obtained by dissolving 2 g of carbon nanotubes, 10 g of ammonium carboxymethyl cellulose, 10 g of ammonium hydrogen carbonate, and 2 g of polyol (glycerin) in 300 ml of water.
A polyol (polyhydric alcohol) is an aliphatic compound having two or more hydroxy groups-OH, and is composed of ethylene glycol, propylene glycol, tetramethylene glycol, diethylene glycol, dipropylene glycol, polyethylene glycol, glycerin, pentaerythritol and the like. Yes, any of these may be used. Here, glycerin was used.

Dispersion treatment This raw material aqueous solution is irradiated with ultrasonic waves for 20 minutes with an ultrasonic homogenizer (manufactured by Mitsui Denki Seiki Co., Ltd., model: UX-600, oscillation frequency 20 ± 1 KHz, maximum output 600 W) to obtain a dispersed aqueous solution of carbon nanotubes. Obtained.

Coating / impregnation and drying treatment on carbon fiber As the carbon fiber, a product of Toray Industries, Inc. was used.
After impregnating the dispersed aqueous solution with the carbon fibers, a baking treatment was performed at 140 ° C. for 30 minutes to evaporate the water content and the ammonia component of the dispersed aqueous solution to dry the surface of the carbon fibers. This impregnation and baking treatment was repeated 3 times.
By the above procedure, a carbon fiber coated with a thin film containing carbon nanotubes was obtained.

Comparative example as an electrode As a comparative example with respect to the above dispersion liquid 1, an evaluation experiment was conducted using carbon fibers (the same product used for CNT-coated carbon fibers 1) that were not coated or impregnated with a dispersed aqueous solution of carbon nanotubes. It was.

Used as an electrode for air magnesium batteries.
Regarding the carbon fibers of Example 1 and Comparative Example, carbon fibers of the same size were used as the air electrode (positive electrode) of the air magnesium battery, and a magnesium plate having a width of 2 cm and a length of 5 cm was used as the negative electrode. Is used as a positive electrode, and ferric chloride is used as an electrolytic solution and is dropped on carbon fibers. At that time, a tester was used to measure how much initial current flows at an open circuit voltage of 2 volts.
As magnesium, "flame-retardant magnesium" manufactured by Gonda Metal Industry Co., Ltd. was used. The tester used was a digital multimeter with an AC / DC clamp manufactured by Kyoritsu Electric Instruments Co., Ltd.
In the comparative example, an initial current of 66.4 mA was obtained. With the CNT-coated carbon fiber 1, an initial current of 538.3 mA could be obtained.

As described above, it was clarified that the CNT-coated carbon fiber 1 had a remarkably large current value as compared with the carbon fiber of the comparative example, and was able to achieve a current density of 8 times or more.

Comparative Example of Dispersion As a comparative example with respect to the dispersion liquid 1, a carbon nanotube dispersion liquid was prepared by the following four methods.
(A) Carbon nanotube dispersion liquid obtained by adding 0.1 g of multi-walled carbon nanotubes (same as above) to 20 ml of water and performing the same ultrasonic treatment as above (B) 0.1 g of multi-walled carbon nanotubes (same as above) and carbon Carbon nanotube dispersion liquid (C) multilayer carbon obtained by adding 0.05 g of black powder (similar to the above) to a solvent consisting of 16 ml of ethanol and 4 ml of water and performing the same ultrasonic treatment as described above. A powder obtained by mixing 0.1 g of nanotubes (same as above) and 0.05 g of graphite nanoplatelets (same as above) was added to a solvent consisting of 16 ml of ethanol and 4 ml of water, and the same ultrasonic treatment as above was performed. A powder obtained by mixing 0.1 g of carbon nanotube dispersion liquid (D) multi-walled carbon nanotubes (same as above), 0.05 g of carbon black powder (same as above), and 0.05 g of graphite nanoplatelets (same as above). Was added to a solvent consisting of 16 ml of ethanol and 4 ml of water, and the same ultrasonic treatment as described above was carried out to obtain a carbon nanotube dispersion liquid.

Dispersibility Test Results The carbon nanotube dispersions (A) to (D) according to the above comparative example and the carbon nanotube dispersions (E) according to the dispersion 1 of the present invention were prepared almost at the same time and sealed and stored in a storage container. It was allowed to stand at room temperature and the progress of 5 days was observed.
Immediately after the ultrasonic treatment, the dispersions (B) to (E) are moderately dispersed, but it is confirmed that the dispersion (E) is particularly excellent in dispersibility.
When 24 hours have passed immediately after the ultrasonic treatment, the dispersibility of the dispersion liquids (B) to (D) is lost, and precipitation of carbon nanotubes is observed. On the other hand, the dispersibility of the dispersion liquid (E) is maintained.
Even after 5 days have passed immediately after the ultrasonic treatment, the dispersion liquid (E) maintains the same dispersibility as immediately after the ultrasonic treatment.

Preparation of nano-carbon material composite The powder obtained by drying treatment from the above dispersion 1 is mixed with a binder such as PTFE (polytetrafluoroethylene) and heat-pressed (200 ° C., 10 tons) to form a molded product. Got This molded product exhibited remarkably excellent electrical characteristics with an electrical resistivity of 0.3 to 0.7 Ω · cm.

The surface of this molded product was photographed with a scanning electron microscope (S-3000H, manufactured by Hitachi High-Technologies Corporation). When the image was taken at a magnification of 15,000 times and a magnification of 6000 times, it was found that the carbon nanotubes were dispersed in the molded product without agglomeration, and the structure had pores formed in some places.

Although the method for dispersing the nanocarbon material, the dispersion liquid for the nanocarbon material, and the nanocarbon material composite have been described above by showing specific embodiments, the present invention is not limited thereto. Those skilled in the art can make various changes and improvements to raw materials, reagents, treatment conditions, treatment procedures, measurement conditions, and measurement methods within a range that does not deviate from the gist of the present invention.
For example, the solvent was prepared by dissolving sodium dodecyl sulfate (0.05 g) in 16 ml of ethanol and 4 ml of water, but 15 ml of ethanol, 5 ml of water and 0.04 to 0.06 g of sodium dodecyl sulfate may be used.
Further, although the ultrasonic irradiation time is set to 20 minutes, it may be set to 15 minutes to 30 minutes.
Regarding the drying treatment, the baking treatment at 140 ° C. for 30 minutes was repeated three times, but the baking treatment at 120 ° C. to 150 ° C. for 20 to 40 minutes may be repeated 2 to 4 times.

≪Sheet-shaped air electrode and its deformation processing≫
FIG. 1 is a diagram showing an example of a carbon fiber sheet used as a base material for an air electrode. FIG. 1A is a perspective view of an example of a carbon fiber sheet, and FIG. 1B is a plan view of another example of a carbon fiber sheet.
The carbon fiber sheet is produced by heating organic fibers such as polyacrylonitrile fibers, pitch fibers, and rayon in an inert atmosphere to desorb elements other than carbon. 90% or more are carbon component fibers.
In the CNT-coated carbon fiber 1 described above in the present invention, a product of Toray Industries, Inc. is used. Compared to the product shown in FIG. 1, the product of Toray Industries, Inc. is made into a cloth by weaving the warp and weft more densely.
As in the example given in FIG. 1 (a), some of them may be skipped and woven. Further, as in the example given in FIG. 1 (b), a loose weave may be used.
Further, it may be a non-woven fabric, for example, a non-woven fabric.

After ultrasonically irradiating the prepared dispersion liquid, a carbon fiber sheet as shown in FIG. 1 is impregnated in the liquid and baked (dried) to form the above-mentioned CNT-coated carbon fiber. To do. Then, this becomes the sheet-shaped air electrode 11. It is considered that CNTs (carbon nanotubes) form a coating film on at least the surface of the sheet-shaped air electrode 11 in a state of being stably dispersed in a state where agglutination is blocked by an agglutination inhibitor. Be done.
FIG. 2 is a diagram showing a state in which a sheet-shaped air electrode (positive electrode) 11 overlaps and is laminated with a negative electrode 14 via a separator sheet 12. The separator sheet 12 is made of an insulator such as a non-woven fabric, and is provided so that the positive electrode and the negative electrode are not electrically short-circuited. Since it is necessary to supply the electrolyte to the negative electrode via the separator sheet 12, the separator sheet 12 is permeable to the electrolyte. In order to improve the performance as a battery, it is desirable that the positive electrode and the negative electrode are as close as possible. For that purpose, it is desirable that the separator sheet 12 is thin.

Since the base material of the sheet-shaped air electrode (positive electrode) 11 is a carbon fiber sheet, the degree of freedom in the area, size, and shape is high. Further, since the separator sheet 12 is also made of a non-woven fabric or the like, the degree of freedom in area, size, and shape is high. On the other hand, since the negative electrode 14 to be overlapped is a metal, as will be described later, it can be bent or deformed to some extent, though not as much as a carbon fiber sheet or a non-woven fabric. Therefore, the degree of freedom in the total area, size, and shape of the positive electrode 11, the separator sheet 12, and the positive electrode 14 overlaid is determined within the range in which the negative electrode can be processed.
This sheet-shaped air electrode has a feature that it can be deformed within the range of the degree of freedom. FIG. 3 is a diagram showing a deformation process in the case of forming an acid battery to be wound around a pipe and arranged. FIG. 3A shows an example in which a sheet-shaped air electrode 11, a separator sheet 12, and a negative electrode 14 are provided concentrically (coaxially cylindrically) from the inside by winding around a pipe 15, and FIG. 3B shows an example. This is an example in which the sheet-shaped air electrode 11, the separator sheet 12, and the negative electrode 14 are provided from the outside. It is desirable that the negative electrode 14 be on the outside for the convenience of replacing the negative electrode with a new one after the negative electrode 14 has melted. For the convenience of supplying air (oxygen) to the sheet-shaped air electrode, it is desirable that the sheet-shaped air electrode 14, which is the positive electrode, is on the outside. Considering the ventilation of the environment in which the acid battery is placed, it will be designed which side should be on the outside.
The shape of the sheet-shaped air electrode 11, the separator sheet 12, and the negative electrode 14 may be cylindrical or C-shaped.
The configuration of the acid battery having a shape that encloses the pipe 15 is an example, and various shapes of the acid battery can be customized according to the convenience of the space shape of the place where the acid battery is desired to be arranged. For example, when installing a battery inside an automobile, the battery can be designed to fit in a small space inside the body. It is also possible to design a battery that fits the human body as a power source for a wearable computer. Furthermore, it is possible to design a battery that matches clothing such as a life jacket.

≪Positive electrode and positive electrode active material of acid battery≫
The sheet-shaped air electrode 11 functions as the positive electrode of the acid battery according to the present invention. And the positive electrode active material is oxygen. Furthermore, when the sheet-shaped air electrode 11 is in contact with the atmosphere, oxygen in the atmosphere is the active material, and when the sheet-shaped air electrode 11 is immersed in the solution (electrolyte solution), it is in the solution. It is the dissolved oxygen of.
Acid batteries are a phenomenon in which electricity is generated when the metal in the negative electrode is melted by acid, but from a different point of view, it is also a phenomenon in which the metal burns (corrodes, oxidizes), and oxygen, which is the positive electrode active material, is transferred from the positive electrode. It can also be seen as a phenomenon in which power is generated when the metal oxide is taken in and generated.
The reaction at the positive electrode is
^{_{2H + O 2 + 2e - →}} 2OH -
Or ^{_{4H + O 2 + 4e - →}} 2H 2 O
Can be expressed as.

≪Negative electrode and negative electrode active material of acid battery≫
The negative electrode is made of a metal containing one or more of magnesium, aluminum, zinc, iron or copper. Pure magnesium is inconvenient to handle because it is flammable (easily oxidized) and causes a violent chemical reaction. Therefore, flame-retardant magnesium is used. "Flame-retardant magnesium" provided by Gonda Metal Industry Co., Ltd. can be used. It is an alloy containing magnesium as the main component, calcium, aluminum, manganese, silicon, zinc, copper, iron, etc., and has achieved flame retardancy. When flame-retardant magnesium is used as the negative electrode, the negative electrode active material is considered to be mainly magnesium.
The reaction at the negative electrode is
_{2HCl + Mg → MgCl 2 + H} 2 + 2e -
Is. Here, MgCl ₂ is soluble in water, so it flows.

≪Acid electrolyte≫
The acidic electrolyte may be an aqueous solution of an acid such as hydrochloric acid or sulfuric acid, or may be an aqueous solution of a salt to be acidic. When magnesium is the negative electrode active material, an aqueous ferric chloride solution can be used.
By bringing the acidic electrolyte into contact with the negative electrode, metal corrosion (oxidation, etching) occurs and power generation is performed. There are roughly three possible methods for bringing the electrolyte into contact with the negative electrode. The first is to immerse the entire stack of the sheet-shaped air electrode 11, the separator sheet 12, and the negative electrode 14 in the electrolyte solution. The second is to impregnate the sheet with a gelled electrolyte solution and bring it into contact with the sheet. Third, the electrolyte solution is dropped or sprayed from the positive electrode side (sheet-shaped air electrode side).
Hereinafter, each of these three cases will be described with a focus on how to control the start, stop, and restart of power generation.

≪Circulate acidic electrolyte solution and control it≫
The separator sheet 12 allows the electrolyte to permeate. Further, the carbon fiber sheet, carbon nanotubes, CMCA (carboxymethyl cellulose ammonium) and the like constituting the sheet-shaped air electrode 11 have electrolyte permeability. Therefore, the acidic electrolyte can reach the negative electrode via the sheet-shaped air electrode 11.
At this time, it is desirable to forcibly create a water flow with a pump or the like to circulate the electrolyte solution so that the electrolyte solution does not stagnate. First, it is to eliminate the produced oxide so as not to inhibit the chemical reaction. Secondly, when a plurality of sets of positive electrode, separator, and negative electrode are laminated, electrolytes and oxides flow in and out only in the peripheral portion of the sheet-shaped air electrode, so that the flow can flow without stagnation. Because it is advantageous. Thirdly, it is also because the dissolved oxygen, which is the positive electrode active material, needs to move appropriately.

FIG. 4 is a diagram showing a system that circulates an electrolyte and controls the start, stop, and restart of power generation. In the configuration shown in FIG. 4A, the acid battery (power generation system) 30 has five sets of combinations of a positive electrode, a separator sheet, and a negative electrode. Insulation is performed between the positive electrode and the negative electrode of the adjacent set so that a chemical reaction does not occur.
The electrolyte solution stored in the first electrolyte tank 31 flows into the acid battery (power generation system) 30 by the pump 41. Further, the electrolyte solution in the acid battery (power generation system) 30 is sucked up by the pump 42 and returned to the first electrolyte tank 31. As a result, the circulation of the electrolyte is realized. By circulating, the electrolyte, the reaction product, and the dissolved oxygen can flow through the space between the positive electrode and the negative electrode in the acid battery (power generation system) 30 without stagnation, and efficient power generation can be continued.
Further, the oxygen aeration device 33 sends air or oxygen in the atmosphere to the first electrolyte tank to expose (expose) the electrolyte solution to air or oxygen. This prevents the dissolved oxygen in the electrolyte solution from dropping.
When it is desired to stop the power generation, the pump 41 is stopped to stop the supply of the electrolyte solution to the acid battery (power generation system) 30, and the pump 42 sucks up and recovers all the electrolyte solution. As a result, the electrolyte does not come into contact with the negative electrode, so that power generation is stopped.

In the configuration of FIG. 4A, as a method of stopping power generation even faster, a plug (not shown) is provided at the bottom of the acid battery (power generation system) 30, the plug is opened, and the gas vent provided at the top is provided. By opening the stopper (not shown), it can be pulled out all at once.

The configuration of FIG. 4B is a system that is relatively suitable for a large facility that can be called a power plant. In FIG. 4B, in addition to the configuration of FIG. 4A, a second electrolyte tank 32, pumps 43, 44, and a nitrogen aeration device 34 are provided. The electrolyte solution in the second electrolyte tank 32 is constantly exposed to nitrogen by the action of the nitrogen aeration device 34, and the dissolved oxygen is kept in a state close to zero. A degassing plug (not shown) is provided in the upper part of the second electrolyte tank 32 so that oxygen expelled from the solution by nitrogen and excessively sent nitrogen can be discharged to the outside. Has been done.
During power generation, the pumps 41 and 42 work as in FIG. 4A, and the dissolved oxygen-rich electrolyte solution moves between the first electrolyte tank and the acid battery (power generation system) 30. Circulate. When the power generation is stopped, the pumps 41 and 42 are stopped and the pumps 43 and 44 are operated to circulate the electrolyte solution in the second electrolyte tank with the electrolyte in the acid battery (power generation system) 30. Let me. Then, the nitrogen aeration measure 34 is put into operation at the same time. As a result, the dissolved oxygen in the electrolyte solution in the acid battery (power generation system) 30 gradually approaches zero, and power generation is eventually stopped.

As another method, it is possible to stop the power generation by recovering the electrolyte solution and sending water.

≪Gel-like electrolyte and power generation stop, power generation restart≫
FIG. 5 is a diagram showing that when an electrolyte is supplied using a gel sheet, a blocking sheet is used to control the start, stop, and restart of power generation.
FIG. 5A shows an example in which the negative electrode 14, the separator sheet 12, the sheet-shaped air electrode 11, the blocking sheet 25, and the electrolyte gel sheet 20 are laminated in this order. The electrolyte gel sheet 20 is a sheet obtained by impregnating a base material suitable for containing a gel, for example, a non-woven fabric containing an electrolyte, here, a gel of ferric chloride. The blocking sheet 25 is a sheet that does not allow the electrolyte to permeate.
As shown in FIG. 5A, in the state where the blocking sheet 25 is arranged, the electrolyte contained in the electrolyte gel sheet 20 does not permeate the blocking sheet 25, so that it does not reach the negative electrode 14. Therefore, since the negative electrode active material does not corrode (combustion, oxidation), power generation does not start.
Power generation is started by removing (pulling out, peeling off) the blocking sheet 25 and allowing the electrolyte of the electrolyte gel sheet 20 to reach the negative electrode 14 via the sheet-shaped air electrode 11 and the separator sheet 12. .. This is because the electrolyte permeates both the sheet-shaped air electrode 11 and the separator sheet 12. At this time, a pressing force may be applied so that the distance between the electrolyte gel sheet 20 and the negative electrode 14 is reduced.
When the power generation is stopped, the blocking sheet 25 is arranged at any position between the electrolyte gel sheet 20 and the negative electrode 14. As a result, the electrolyte is no longer supplied to the negative electrode, and corrosion (combustion, oxidation) of the negative electrode active material is stopped.

FIG. 5B shows an example in which the negative electrode 14, the separator sheet 12, the blocking sheet 25, the electrolyte gel sheet 20, and the sheet-shaped air electrode 11 are arranged in this order. From the viewpoint of battery performance, it is desirable that the distance between the negative electrode 14 and the sheet-shaped air electrode 11 is short. Therefore, it is considered desirable to make the electrolyte gel sheet 20 thinner. When power generation becomes impossible due to a decrease in the electrolyte impregnated in the electrolyte gel sheet 20, the electrolyte gel sheet 20 is replaced with a new one. Alternatively, the electrolyte is supplied to the electrolyte gel sheet 20 via the sheet-shaped air electrode 11.
The functions of the cutoff sheet 25 for starting power generation, stopping power generation, and restarting power generation are the same as in the case of FIG. 5A.

FIG. 6 is a diagram showing that when an electrolyte gel sheet is used, the start, stop, and restart of power generation are controlled by inserting and removing the gel sheet itself.
In FIG. 6A, the negative electrode 14, the separator sheet 12, the sheet-shaped air electrode 11, and the electrolyte gel sheet 20 are laminated in this order, and the electrolyte of the electrolyte gel sheet 20 is the sheet-shaped air electrode 11 in this state. , Reach the negative electrode 14 via the separator sheet 12. Therefore, power is generated.
When stopping the power generation, the electrolyte gel sheet 20 is pulled out or peeled off.
To resume power generation, the electrolyte gel sheet 20 is returned to the position shown in FIG. 6A again.

In FIG. 6B, the negative electrode 14, the separator sheet 12, the electrolyte gel sheet 20, and the sheet-shaped air electrode 11 are laminated in this order.
The electrolyte gel sheet 20 is pulled out or peeled off to stop power generation. At this time, instead of peeling off the electrolyte gel sheet 20 alone, the sheet-shaped air electrode 11 and the electrolyte gel sheet 20 may be peeled off together.
To resume power generation, return to the layout shown in FIG. 6 (b).

≪Scalability by stacking≫
As shown in FIG. 4, a plurality of sets of combinations including the negative electrode 14, the separator sheet 12, and the sheet-shaped air electrode 11 can be laminated. At this time, the voltage can be increased by electrically connecting in series. The current can be increased by connecting in parallel.

≪Planned power generation by dropping or spraying acidic electrolyte solution≫
FIG. 7 is a diagram showing a configuration when the acidic electrolyte is dropped or sprayed from the positive electrode side.
FIG. 7A shows the electrolyte solution dropping device 50 from above, that is, from the side of the sheet-shaped air electrode 11 with respect to the one in which the negative electrode 14, the separator 12, and the sheet-shaped air electrode 11 are arranged horizontally in this order. The state of dropping is shown by. The dropping of the electrolyte solution can be continued by dropping a fixed amount. Alternatively, it may be a method of intermittently dropping a predetermined amount for a predetermined time, then stopping and restarting for a predetermined time. This dropping makes it possible to supply a necessary and sufficient electrolyte solution that meets the demand for electric power.
In the acid battery according to the present invention, the acidic electrolyte functions as an acid to oxidize the negative electrode active material, so that the power generation is stopped when the supplied electrolyte solution is exhausted. Therefore, there is an advantage that the electrolyte is not supplied more than necessary and wasteful power generation is not required.

A control device 60 is provided to systematically control the electrolyte supply. The peak time of the daily power demand, the weekly power demand, the yearly power demand, etc. is calculated from the past statistical data and the power is systematically generated.

FIG. 7B shows an example in which the electrolyte solution spraying device 55 is provided instead of the electrolyte usufruct dropping device 50. Dropping and spraying have almost the same effect. In the case of spraying, there is an advantage that oxygen (positive electrode active material) can be supplied at the same time as the electrolyte.
Further, in the case of spraying, as shown in FIG. 7C, the negative electrode 14, the separator 12, and the sheet-shaped air electrode 11 can also be used when they are upright.

In the acid battery (power generation system) according to the present invention, any one of the negative electrode active material (for example, magnesium), the electrolyte (for example, ferric chloride), and the positive electrode active material (oxygen) is controlled. This makes it possible to control the start, stop, and restart of power generation. Therefore, it is suitable for constructing equipment such as a system and a plant suitable for planned power generation by a control device.

The air electrode, acid battery, and power generation system of the present invention can be used as an emergency power source or a regular power source in various places such as an auxiliary power generation system in a power plant, manufacturing equipment, a hospital, and a ship.

11 Sheet-shaped air electrode 12 Separator sheet 14 Negative electrode 15 Pipe 20 Electrolyte gel sheet 25 Blocking sheet 30 Acid battery (power generation system)
31 First electrolyte tank 32 Second electrolyte tank 33 Oxygen aeration device 34 Nitrogen aeration device 41, 42, 43, 44 Pump 50 Electrolyte solution dropping device 55 Electrolyte solution spraying device 60 Control device

Claims (16)

A sheet-like air electrode made of a carbon fiber sheet having a film-like substance containing carbon nanotubes on its surface is used as a positive electrode.
A metal containing magnesium, aluminum, zinc, iron or copper is used as the negative electrode.
An acid battery in which an acidic electrolyte is arranged between the positive electrode and the negative electrode.
The acidic electrolyte is in the form of a gel and is provided as a gel sheet impregnated in the sheet.
The gel sheet comes into contact with the negative electrode via a blocking sheet that does not allow electrolytes to permeate and can be inserted and removed, generates electricity with the blocking sheet removed, and stops power generation with the blocking sheet inserted. battery. Wherein in accordance with the space shape of the place to put the sheet-like air electrode, the area of the carbon fiber sheet, the dimensions, acid battery according to claim 1, wherein the shape is capable of changing. The acid battery according to claim 1 or 2 , wherein the negative electrode is arranged so as to be replaceable, and when the negative electrode is dissolved, the negative electrode is replaced with a new negative electrode. A sheet-like air electrode made of a carbon fiber sheet having a film-like substance containing carbon nanotubes on its surface is used as a positive electrode.
A metal containing magnesium, aluminum, zinc, iron or copper is used as the negative electrode.
An acid battery in which an acidic electrolyte is arranged between the positive electrode and the negative electrode.
The acidic electrolyte is in the form of a gel and is provided as a gel sheet impregnated in the sheet.
The gel sheet is removable, and the acid battery is characterized in that the contact between the electrolyte and the negative electrode is cut off by removing the gel sheet, and the contact between the electrolyte and the negative electrode is realized by inserting the gel sheet. The acid battery according to claim 4 , wherein the area, size, and shape of the carbon fiber sheet can be changed according to the spatial shape of the place where the sheet-shaped air electrode is arranged. The acid battery according to claim 4 or 5 , wherein the negative electrode is arranged so as to be replaceable, and when the negative electrode is dissolved, the negative electrode is replaced with a new negative electrode. A sheet-like air electrode made of a carbon fiber sheet having a film-like substance containing carbon nanotubes on its surface is used as a positive electrode.
A metal containing one or more of magnesium, aluminum, zinc, iron or copper is used as the negative electrode.
A power generation system in which a plurality of acid batteries in which an acidic electrolyte is arranged between the positive electrode and the negative electrode are arranged and electrically connected .
Before SL acid electrolyte is a gel-like, provided as gel sheet impregnated into a sheet,
The gel sheet comes into contact with the negative electrode via a blocking sheet that does not allow electrolytes to permeate and can be inserted and removed, generates electricity with the blocking sheet removed, and stops power generation with the blocking sheet inserted. system. The area, size, and shape of the carbon fiber sheet constituting the positive electrode can be changed according to the spatial shape of the place where the positive electrode is arranged.
The power generation system according to claim 7, wherein the negative electrode is deformed according to a change in the area, dimensions, and shape of the positive electrode. A sheet-like air electrode made of a carbon fiber sheet having a film-like substance containing carbon nanotubes on its surface is used as a positive electrode.
A metal containing one or more of magnesium, aluminum, zinc, iron or copper is used as the negative electrode.
A power generation system in which a plurality of acid batteries in which an acidic electrolyte is arranged between the positive electrode and the negative electrode are arranged and electrically connected .
Before SL acid electrolyte is a gel-like, provided as gel sheet impregnated into a sheet,
The gel sheet is removable, and the power generation system is characterized in that the contact between the electrolyte and the negative electrode is cut off by pulling out the gel sheet, and the contact between the electrolyte and the negative electrode is realized by inserting the gel sheet. The area, size, and shape of the carbon fiber sheet constituting the positive electrode can be changed according to the spatial shape of the place where the positive electrode is arranged.
The power generation system according to claim 9, wherein the negative electrode is deformed according to a change in the area, size, and shape of the positive electrode. Any one of claims 7 to 10, wherein the reaction stop device realizes a reaction stop state in which the contact between the negative electrode and the acidic electrolyte is cut off, or the contact between the positive electrode and oxygen is cut off. The power generation system described in the section. The power generation system according to claim 11 , wherein the reaction stop device can release the reaction stop state and start power generation again. A sheet-like air electrode made of a carbon fiber sheet having a film-like substance containing carbon nanotubes on its surface is used as a positive electrode.
A metal containing one or more of magnesium, aluminum, zinc, iron or copper is provided interchangeably with a new one at the time of dissolution to serve as a negative electrode.
A separator having electrical insulation and transmitting an electrolyte is provided between the positive electrode and the negative electrode.
Power generation having an acidic electrolyte supply device that drops or sprays an amount of acidic electrolyte required for power generation from the positive electrode side to reach the negative electrode on a laminate in which the positive electrode, the separator, and the negative electrode are laminated. system. The power generation system according to claim 13 , further comprising an acidic electrolyte supply control device for controlling the supply amount of the acidic electrolyte by the acidic electrolyte supply device, and realizing planned power generation. A method for manufacturing a sheet-shaped air electrode made of a carbon fiber sheet having a film-like substance containing carbon nanotubes on its surface.
A step of producing an aqueous solution of raw materials by dissolving carbon nanotubes, ammonium carboxymethyl cellulose, ammonium hydrogencarbonate, and glycerin in water to obtain an aqueous solution of raw materials.
An ultrasonic irradiation step of irradiating the raw material aqueous solution with ultrasonic waves with an ultrasonic homogenizer to obtain a dispersed aqueous solution, and
An impregnation step of impregnating the dispersed aqueous solution obtained in the ultrasonic irradiation step with a carbon fiber sheet, and an impregnation step.
A method for producing a sheet-like air electrode, which comprises a drying step of drying the impregnated carbon fiber sheet. The method for manufacturing a sheet-shaped air electrode according to claim 15 , wherein the impregnation step and the drying step are repeated.

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